郑汴公路路尘、路沟底泥和路旁土壤重金属分布

Spatial Distribution and Contamination of Heavy Metals in Road Dust,Sediment in Roadside Ditch and Roadside Soils along Zhengzhou-Kaifeng Highway

以运营40多a的郑汴公路杏花营路段为研究对象,在采样断面上，按离开公路路基的距离不同布设土壤采样点,用F-AAS法测定土壤中Ni，Cu，Zn和Cr的含量。用GF-AAS法测定Pb和Cd的含量,结果表明，汽车尾气排放、汽车机件间以及车轮与路面间磨损产生的颗粒物导致路面粉尘、路沟底泥和路旁土壤重金属积累；公路北侧路沟和土壤采样点的重金属含量普遍高于公路南侧相应采样点；路面粉尘中大多数重金属含量低于路沟底泥，而高于对照样和公路两侧300m范围内的土壤重金属平均含量；路旁土壤中大部分重金属的最高含量不在路基处，而出现在距路基20-50m之间，然后逐渐下降至对照值；郑汴公路交通对两侧土壤环境的影响范围超过300m，300m范围内均发生了不同程度的重金属污染，其中100m范围内发生了中度至重度污染；Cd，Cr和Pb是最主要的公路源污染元素。

To understand the spatial distribution and contamination of heavy metals along roads and roadsides, Zhengzhou-Kaifeng highway, having operated over 40 a, was chosen as the research object. A sampling transect is perpendicular to the highway. Samples were collected on the line of this transect at a specific interval. The concentrations of Ni, Cu, Zn and Cr in these samples were determined by the flame atomic absorption spectrometry （F-AAS）, and Pb and Cd by the graphite furnace atomic absorption spectrometry （GF-AAS）. The research results show that heavy metals, except for Ni in road dust, sediment in roadside ditch, and roadside soils along the highway, have accumulated obviously because of trail gas from vehicles, wearing of engine and brakes, and wearing between tires and road surface. The heavy metal concentrations in road dust and roadside soils on the northern side of the highway are higher than those on the southern side. The concentrations of most heavy metals in the road dust are lower than those in the sediments in roadside ditch, but higher than the average values in the control samples and roadside soils within 300 m from the highway. The highest concentrations of most heavy metals, except for Cu in soils, are at 20 to 50 m away from the roadbed, and then gradually decrease to the control values. The incidence of highway traffic exceeds over 300 m from the highway. The zones within 100 m from the roadbed have been moderately or heavily polluted by heavy metals, and Cd, Cr and Pb are the main pollutants originated from the highway.